[rrd-users] peak from multiple databases over time

[Jan Terstegge]

Hi everyone,

I'm looking for a way to calculate the peak value from multiple databases (Backup 
usage of different servers).

This is the setup:
20 databases, each of them type Gauge, cf is Avg with 210240 rows.

My graph looks fine, it is an area for the first database, the others are stacked 
on top. When I look at the graph, an overall backup usage of 6 TB is visible.

But this problem occurs:
I want a description line, which lists the largest value, calculated over all 
databases.

DEF for each database is:
DEF:l${NR}=${DATAFILE}.rrd:ds1:AVERAGE where NR is 0..19

My CDEF is:
cdef:ctotal=${RPNCALC} where RPNCALC is each ds added (0,l0,+,l1+,l2...)

And then I vdef' it:
VDEF:vtotal=ctotal,MAXIMUM

On this point the graph and the commentline vary: I have a graph showing nearly 6 
TB on it's highest peak, but the GPRINT gives me only 5,2 TB.

Does anyone have an idea where my mistake is?


Thanks,
Jan